This invention relates to current sources, and in particular, current sources capable of providing a high power supply rejection ratio (xe2x80x9cPSRRxe2x80x9d).
PSRR refers to the change in input offset voltage of an operational amplifier (xe2x80x9cop-ampxe2x80x9d) to the change in the power supply voltage that causes it. The offset voltage refers to the difference in voltage at the two inputs of an op-amp required to bring the output voltage to zero.
The present invention improves on the topology of a conventional current source by interposing an RC circuit and additional MOS between the output of the buffer and the output of the current source. The topology of the present invention advantageously provides a clean current output by shunting noise to ground.